Microbial iron transport via a siderophore shuttle: A membrane ion transport paradigm
The siderophore-mediated iron transport in A. hydrophila was found to occur by means of a siderophore transport system with a very low specificity. At least two groups of transport systems were found to be present in A. hydrophila, of which one of them was indiscriminant towards a series of iron-siderophore complexes and iron complexes of siderophore analogs. The Fe(III) uptake proceeds via a redox-free ligand exchange mechanism in which iron from an iron-siderophore complex exchanges with a receptor-bound apo-siderophore. This exchange process is believed to be proton driven and is triggered by a pH gradient inside the β-barrel of the receptor.